Question

【题目】— This kind of sports is exciting.
— Yes, but it's dangerous. One can't do it ____ he or she has got some training.
A.if
B.after
C.when
D.unless

Answer 1

【答案】D
【解析】句意：——这种运动是令人兴奋的。——是的，但它是危险的。人不可以做它，除非受过一些训练。If如果；after在……之后；when当……的时候；Unless除非。结合句意可知该选D。